If the bass was perfect before the string change, and they are heavier - then yep, truss rod to compensate for the change in tension pulling the neck, and then a tweak of the saddles/bridge to compensate for the truss rod adjustment. I'd probly check the nut slots to see if they were ok and there was no binding with the new strings. On a good day, 15 mins tops.
Oh and don't forget - Righty tighty, lefty Lucy..